1. Field of the Invention
The present invention relates to an image reader, an image reading apparatus, and a reading resolution setting method, and particularly to the art of changing a reading resolution of the image reader that may be employed by the image reading apparatus and may be used in the reading resolution setting method.
2. Discussion of Related Art
There has conventionally been known an image reading apparatus, employed by, e.g., a facsimile machine or a copying machine, that includes a contact image reader (CIS) that reads an image according to a start signal and a clock pulse signal.
In addition, there has been proposed such an image reading apparatus that can change a reading resolution of an image reader thereof that is to be used to read an image. However, the image reading apparatus suffers a problem that an exclusive signal line is needed to indicate the reading resolution to the image reader, which leads to increasing the production cost of the apparatus.
In this background, Japanese Patent Publication No. 2000-101803 discloses an image reading apparatus that can change, according to a reading resolution to be indicated to an image reader thereof, a pulse width of a start signal, and thereby change a number of pulses of a clock pulse signal that occur while the start signal takes an ON state (i.e., a high level), so that the reading resolution is indicated to the image reader without using an exclusive signal line.
However, the above-indicated image reading apparatus suffers a problem that the start signal needs to take the ON state for an increased time duration, for the purpose of changing the number of pulses of the clock signal according to the reading resolution and accordingly the image reader cannot commence an image reading operation for the increased time duration.